I tested with this little text. (Don't worry about the words, I pasted repetition into it.) It gave me 3 text files as a result.
Note: the minimum of 5 lines is probably causing trouble. as the Help tells you, a line is from one <Enter> to the next, which is approx one paragraph to the next if your text is nicely formatted. (Not nicely = with an <Enter> at the end of each line in my opinion!)
I'm writing the new 64 bit WS. When I do the Splitter function I can try to reduce the minimum to 1 line.